The present invention relates in general to electronic circuits, and more particularly to low noise oscillators circuits.
Oscillator circuits are well known in the art, and may be generally described as circuits which generate an output signal, the frequency of which is determined by a connecting “tank” or resonant circuit. Oscillator circuits (including voltage controlled oscillators or VCOs) are important circuits in today's electronics as they form the crucial building blocks in larger circuits such as frequency synthesizers, modulators and demodulators, and clock recovery circuits typically employed in numerous telecommunication products.
In many instances, the performance of these telecommunications devices is limited by the oscillator's “phase noise,” which can be generally described as the random variation in the phase or frequency of the output signal. In essence, the oscillator phase noise places a limit on how precisely the output frequency of the oscillator can be generated. This loss in accuracy translates into errors in the transmission and reception of information. What is therefore needed is an oscillator circuit which exhibits improved phase noise performance.